We presented an algorithm that can constructs digitized databases from various graphical representa-tions such as thermodynamic property charts by utilizing a desk-top digitizer properly. It is found that any types of usual model-oriented process calculation such as interpolations and process optimization can be equivalently accom-plished with these digitized property charts. As the first illustration, the compressibility factors for any reduced tem-perature and pressure can be evaluated quickly and accurately by digitized Pitzer’s Z-chart with linear and cubic spline interpolation methods. As the second illustration, optimum operation paths which give maximum separation yield with the least of energy demand can be sought with the digitized property chart for the supercritical extraction process of soybean oil with carbon dioxide.